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Theorem cnconst 23138
Description: A constant function is continuous. (Contributed by FL, 15-Jan-2007.) (Proof shortened by Mario Carneiro, 19-Mar-2015.)
Assertion
Ref Expression
cnconst (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ (𝐡 ∈ π‘Œ ∧ 𝐹:π‘‹βŸΆ{𝐡})) β†’ 𝐹 ∈ (𝐽 Cn 𝐾))

Proof of Theorem cnconst
StepHypRef Expression
1 fconst2g 7199 . . . 4 (𝐡 ∈ π‘Œ β†’ (𝐹:π‘‹βŸΆ{𝐡} ↔ 𝐹 = (𝑋 Γ— {𝐡})))
21adantl 481 . . 3 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ 𝐡 ∈ π‘Œ) β†’ (𝐹:π‘‹βŸΆ{𝐡} ↔ 𝐹 = (𝑋 Γ— {𝐡})))
3 cnconst2 23137 . . . . 5 ((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ) ∧ 𝐡 ∈ π‘Œ) β†’ (𝑋 Γ— {𝐡}) ∈ (𝐽 Cn 𝐾))
433expa 1115 . . . 4 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ 𝐡 ∈ π‘Œ) β†’ (𝑋 Γ— {𝐡}) ∈ (𝐽 Cn 𝐾))
5 eleq1 2815 . . . 4 (𝐹 = (𝑋 Γ— {𝐡}) β†’ (𝐹 ∈ (𝐽 Cn 𝐾) ↔ (𝑋 Γ— {𝐡}) ∈ (𝐽 Cn 𝐾)))
64, 5syl5ibrcom 246 . . 3 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ 𝐡 ∈ π‘Œ) β†’ (𝐹 = (𝑋 Γ— {𝐡}) β†’ 𝐹 ∈ (𝐽 Cn 𝐾)))
72, 6sylbid 239 . 2 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ 𝐡 ∈ π‘Œ) β†’ (𝐹:π‘‹βŸΆ{𝐡} β†’ 𝐹 ∈ (𝐽 Cn 𝐾)))
87impr 454 1 (((𝐽 ∈ (TopOnβ€˜π‘‹) ∧ 𝐾 ∈ (TopOnβ€˜π‘Œ)) ∧ (𝐡 ∈ π‘Œ ∧ 𝐹:π‘‹βŸΆ{𝐡})) β†’ 𝐹 ∈ (𝐽 Cn 𝐾))
Colors of variables: wff setvar class
Syntax hints:   β†’ wi 4   ↔ wb 205   ∧ wa 395   = wceq 1533   ∈ wcel 2098  {csn 4623   Γ— cxp 5667  βŸΆwf 6532  β€˜cfv 6536  (class class class)co 7404  TopOnctopon 22762   Cn ccn 23078
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-8 2100  ax-9 2108  ax-10 2129  ax-11 2146  ax-12 2163  ax-ext 2697  ax-sep 5292  ax-nul 5299  ax-pow 5356  ax-pr 5420  ax-un 7721
This theorem depends on definitions:  df-bi 206  df-an 396  df-or 845  df-3an 1086  df-tru 1536  df-fal 1546  df-ex 1774  df-nf 1778  df-sb 2060  df-mo 2528  df-eu 2557  df-clab 2704  df-cleq 2718  df-clel 2804  df-nfc 2879  df-ne 2935  df-ral 3056  df-rex 3065  df-rab 3427  df-v 3470  df-sbc 3773  df-csb 3889  df-dif 3946  df-un 3948  df-in 3950  df-ss 3960  df-nul 4318  df-if 4524  df-pw 4599  df-sn 4624  df-pr 4626  df-op 4630  df-uni 4903  df-iun 4992  df-br 5142  df-opab 5204  df-mpt 5225  df-id 5567  df-xp 5675  df-rel 5676  df-cnv 5677  df-co 5678  df-dm 5679  df-rn 5680  df-res 5681  df-ima 5682  df-iota 6488  df-fun 6538  df-fn 6539  df-f 6540  df-fv 6544  df-ov 7407  df-oprab 7408  df-mpo 7409  df-1st 7971  df-2nd 7972  df-map 8821  df-topgen 17395  df-top 22746  df-topon 22763  df-cn 23081  df-cnp 23082
This theorem is referenced by:  xrge0mulc1cn  33450  cxpcncf2  45169
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